Since the dual-clutch transmission adopts a dual-clutch system and a conventional fixed-axle gear transmission, it has a higher transmission efficiency, a shorter system power interruption duration during a gear shift, and favorable driving comfort and fuel economy. The Dual-clutch transmission has gradually become a hot spot in the development of the transmission industry since it was successfully commercialized and installed in automobiles by Volkswagen.
A Chinese Patent CN 102084153A discloses a dual-clutch transmission having two input shafts connected to a first clutch or a second clutch, respectively. Two driving shafts, provided above and below the input shafts, transmit a torque to a differential via driving gears on the driving shafts. To achieve a reverse gear, another shaft is further provided above the second driving shaft. The reverse gear is achieved as follows: a torque of the first input shaft is transferred to a shaft for the reverse gear via a corresponding gear pair and then transferred to the second driving shaft via a reverse-gear gear, and finally the torque is applied to the differential via the driving gears of the driving shafts. In such a dual-clutch transmission, the arrangement of providing a specific shaft for the reverse gear will largely limit the arrangement of a gear shift mechanism and the overall structural arrangement of the transmission, preventing the realization of a compact structural form.
A Chinese Patent CN1910387B discloses a seven-gear dual-clutch transmission, which is provided with an intermediate gear for realizing a reverse gear on a second driving shaft, this intermediate gear having different transmission stages; meanwhile, a third driving shaft, with a reverse-gear synchronizer, a reverse-gear driven gear, a primary reduction driving gear and the like provided thereon, is further provided in this dual-clutch transmission, and the power of the reverse gear is output through the third driving shaft. This transmission has two input shafts and three output shafts in total, which hampers the realization of a compact structural form. In addition, because this dual-clutch transmission employs five synchronizers, and a six-gear and reverse-gear synchronizer works only with its half side, it results in a large number of parts and a complicate structure of a gear shift fork for the six-gear and reverse-gear synchronizer.